1. Field of the Invention
The present invention generally relates to the field of integrated circuit communications systems. In particular, the present invention is directed to communication systems and methods using a microelectronics power distribution network.
2. Background of the Invention
As the density of integrated circuits, number of functions, and the need for supervisory control for chip characteristics such as power and heat, increases, the need exists to exploit every communication channel available on the die or chip. This has traditionally been done by running more wires and increasing the number of layers of metal on a die. Studies have shown that as the number of layers increase, the actual routability of these new wires plateaus because of the inability to create vias to other metal layers due to the density of existing wires and vias.
The use of radio transmission of information from one location on the chip to another has been investigated as an additional communication avenue. Also the use of light transmission through the oxide layers has been explored.
The use of communications over alternating current macro utility lines has been used for many years. For example, power line companies have used communications over power lines to read electric meters, and consumers have used home control systems, such as the X10 system, to switch lights using 110 volt power lines throughout the home. However, the use of a microelectronics power distribution network for communication has heretofore not been examined or implemented.
U.S. Pat. No. 3,938,129 to Smither describes data transmission over a line carrying alternating current power. U.S. Pat. No. 5,452,344 to Larson describes a frequency shift key (FSK) carrier communication system for transmitting and receiving data on electric utility lines, particularly for communication with electric utility meters and vending machines. U.S. Pat. No. 5,835,005 to Furukawa et al. describes power line communication systems employing relay stations, particularly for use with large refrigerated container carriers and communication with the refrigerated containers over electrical lines. U.S. Pat. No. 6,373,377 to Sacca et al. describes a power supply with coupling for using the AC power line to communicate digital data from within a digital device, such as a computer. The prior uses of power line communication deal only with transmissions over utility and house level alternating current power lines, and do not address the particular difficulties inherent to power distribution networks of microelectronics chips or communications over direct current power lines.
The power systems of a microelectronics chip are extremely sensitive to fluctuations in power and to the noise carried on that power. In addition the power systems are susceptible to interferences produced by the integrated circuits of the chip itself. Merely keeping the power balance correct for the circuits of the chip is in itself a difficult task. The introduction of additional signals onto the power distribution network makes it more difficult to achieve this balance. The power environment of a microelectronics chip differs widely from the more robust utility and household power lines previously used to transfer information. Typical microelectronics chips work with power that ranges from 0.7 volts (V) to 5 V, which is in comparison to the far greater voltages of utility and household power lines. Although future voltages on microelectronic chips may be higher, the current trend is toward lower voltages. Additionally, utility and household power lines have far greater voltages than present or projected voltages of power distribution networks on microelectronic chips, even if the voltages on microelectronic chips were to go higher. Utility and household power lines have much greater levels of power noise than do power distribution networks of microelectronics chips allowing them to carry additional interference more readily. It is far more difficult a task to place an additional signal on the power distribution network of a microelectronics chip without disrupting the overall noise tolerance of the chip or the power bus driving the chip.
Accordingly, there is a need for new communications avenues on microelectronics chips that can take advantage of the pre-existing power distribution network on the chip itself.